The invention relates generally to keyboards used for data entry and, more particularly, to such keyboards having adjustable splay and pronation.
The frequent use of keyboards for interfacing with computers and other devices can cause serious physical injury and pain to the wrists and other areas of the arms of users. This is generally caused by repetitive motion of the user's fingers on the keys of the keyboards. These disorders are commonly known as cumulative-trauma disorders or repetitive-motion injuries. As the number of individuals using keyboards on a continuous and repetitive basis has been increasing, these types of disorders have become more prevalent. Such repetitive use can also cause physical damage to the wrist, particularly to the carpal tunnel of the wrist. Such damage to the carpal tunnel, known as Carpal Tunnel Syndrome, can cause serious weakening of the hands and reduction in dexterity.
Tests indicate that a standard monoplane keyboard, i.e., a keyboard defined in but one plane and lying generally fiat on a table, exacerbates the problems associated with repetitive-motion injuries. The monoplane keyboard forces the user to rotate his or her forearms from a relaxed position to an extreme position so that the fingertips of each hand are horizontal. Furthermore, both wrists must be flexed away from the thumb side of the hand in order to line up the fingertips with the longitudinal rows of keyboard keys. It has been determined that repositioning the keyboard to permit a more "natural" or unflexed positioning of the forearms and hands significantly reduces the stress on the wrists and elbows, thereby reducing the instances of repetitive-motion injuries resulting from the use of keyboards. To this end, several keyboard designs have been developed.
For example, U.S. Pat. No. 4,509,873 issued to Ryan discloses a "split" keyboard in which keys are apportioned between two smaller boards, or "demi-boards," which may be configured into an A-frame orientation to effect the pronation of the keyboard. The keyboard incorporates a base member having a distal face oriented away from the user and a proximate face oriented adjacent the user. Adjustment from a fiat horizontal position to an angled position is achieved by raising the central portion of the demi-boards from the fiat base member. The base member is angled so that the distal side is higher than the adjacent side. Additionally, the intersection point of the two demi-boards is perpendicular to the plane of the top face of the base member.
In another example, U.S. Pat. No. 4,597,681 to Hodges discloses an adjustable keyboard having a base member and a pair of demi-boards which may be raised at their joining edge into an A-frame configuration to adjust the pronation. Furthermore, each demi-board may be pivoted within its respective plane about an axis perpendicular to that plane to adjust the splay, in addition to the pronation, of the keyboard. Hodges provides a generally fiat base member with a generally dish-shaped surface of the keys. The keys may be positioned in a non-planar manner on each demi-board.
Each of these A-frame type of adjustable keyboards, while representing an improvement over the m,n,plane keyboard in terms of hand positioning, do not generally provide sufficient optimization of wrist and forearm positions when the fingers are placed in contact with the key faces. More particularly, these keyboards still force the user to bend the wrists upwardly and/or outwardly to align the fingertips with the keys on each demi-board. It is not possible, if one is to maintain proper finger alignment to the keys, to orient the wrists in linear alignment with the forearm, as the planes of the demi-boards in an A-frame orientation are still parallel to the proximal-distal axis of the keyboard base. In other words, the user is still forced into a position where his wrists are bent backwards to some degree forming an angle with the forearm, in order to properly contact such a keyboard.
As a consequence, keyboards have continued to evolve, with more recent designs utilizing adjustable demi-boards which may be raised, with respect to a base member, to a position wherein the distal edge of the demi-boards is oriented inwardly as compared to the adjacent edges of the demi-boards. As a result, when compared to the A-frame configurations, the demi-boards more closely parallel the forearms of the user so that the fingertips of the user may contact the keys on the demi-boards while maintaining improved linear alignment of the wrist and forearms.
As an example of a more recent keyboard design, U.S. Pat. No. 5,351,066 to Rucker et al. discloses an adjustable keyboard in which a pair of demi-boards are extendable from a retracted, flat position to an extended, tetrahedral position wherein the distal side of one of the demi-boards is closer to the other demi-board than the proximate side. While the Rucker keyboard provides for adjustment of both the splay and the pronation of the keyboard, it does so with only a single degree of freedom, i.e., the splay and pronation can not be independently adjusted. Moreover, Rucker does not provide for independent adjustment of the separate demi-boards either.
U.S. Pat. No. 5,228,791 to Fort cures some of the deficiencies of the Rucker invention in a keyboard arrangement in which a conventional keyboard is divided into two sections, each of which is separably supported on a joint which is freely rotatable and pivotable. The joint however is unwieldy and would not be feasible in a portable personal computer such as a "notebook" or "laptop" computer.
Therefore, what is needed is a keyboard in which the splay and the pronation thereof may be independently adjusted and which would be compatible with the space constraints of a relatively small portable computer.